CYA/Algea question

[markayash]

I have been battling green or mustard algae for the last 6 weeks. First the water is crystal clear, see the bottom perfect..But the green algae is growing on the walls and sides in patches and is hard to brush off..When I clean the cartridge filter it's full of a mustard looking dirt which makes me wonder.

Now all test are good, TC is around 6 ( I have shocked it at least 4 times to the level that it should have killed algae for the whole block ..Only test that is out of range is CY which is around 90, not sure how it got so high, just drained and refilled 4 months ago..One mistake I did was used test strips for the CYA before I bought the test kit and it kept saying CYA was zero.

Would the CYA of 90 impact algae?

 

[PAGirl]

You get algae when your FC isn't high enough for your CYA level. Pool School - Chlorine / CYA Chart not brushing and poor circulation of the water can add to it. If you regularly fall below the minimum (for a CYA OF 90 that's 7 FC) you will keep seeing algae.

When you say "shock" are you talking the pool store variety of a one time dump of a lot of chlorine, or the TFP SLAM? Pool School - SLAM - Shock Level And Maintain

And lastly, have you read this Pool School - ABCs of Pool Water Chemistry yet?

You would want to get your CYA down by draining some water before you attempt to SLAM.

 

[Texas Splash]

Yes, absolutely if your FC is not high enough. For a CYA of 90, your FC needs to be 35 to perform a TFP "SLAM" link below. If you've never read that page, you'll see it's much different than what most people think of when they do a pool store "shock". To "SLAM", you must have one of the recommended test kits - either a TF-100 (link below) or Taylor K-2006C. One of those is a must. Let us know if you have any questions about the test kit or SLAM instructions. Have a nice evening.

 

[DKT113]

IF your CYA is 90 FC of 6 is not going to get you anywhere.

You are going to be asked to post a full set of numbers, so you may as well do that and then someone will speak to you about Mustard Algae, your 90 CYA, 6 FC and why we don't "shock" x amount of times we SLAM with precision and consistency.

 

[markayash]

I started using the liquid chlorine..One question is to move FC from 6 to say 35 for example how many gallons of liquid would it take..I had a similar problem once before and hired a pool lady who had me do 15 pds shock and then she said in 24 hours chlorine will be zero and do it again..It did drop to zero and the 2nd shock took care of it..It was a 40,000 gallon pool ( big deep pool )compared to this which is closer to 20,000 gallons

 

[jblizzle]

Your question is why we have the handy dandy PoolMath.

 

[PAGirl]

You use this http://www.troublefreepool.com/calc.html to calculate how much. Make sure to put in the correct pool volume, and your actual reading in the left, the target in the right column. Read the link I provided above on the SLAM process.

 

[markayash]

Thanks for the links..i did buy the test kit and learning..As a rule of thumb how do a gallon of 10% and a bag of shock compare..i have to fix a few tiles so will drain and refill some they shock it

 

[jblizzle]

depends on what your bag of "shock" really is ... it could be 5+ different things.

I can say that all the "shock" bags add extra junk that you typically do not want.

PoolMath will show you at the bottom in the Effects of Adding Chemicals area what each product will do.

 

[markayash]

Tt works but like to understand why 4 gallons didn't work but 5 did? I even shocked it twice using 4 each time and didn't see to kill it..But when I added 5 it seemed to clear almost over night?

 

[jagger2005]

Tt works but like to understand why 4 gallons didn't work but 5 did? I even shocked it twice using 4 each time and didn't see to kill it..But when I added 5 it seemed to clear almost over night?

I cannot give you any knowledge as to the why in your scenario. I have always been a TFP'er and have never put anything in my pool with understanding what the effects would be. When the pool lady told you to add 15 lbs of shock and in 24 hours, FC will be back to zero so go ahead and 15 more lbs. By chance, it cleared so you might think she was spot on. If by chance, it had not cleared after batch 2, my guess would be when you called her, she would have told you to add 15 lbs again.

I think I read that you have a test kit. You are half way there. Read up on the links that PAGirl posted. I know it appears there is a lot information and testing to understand. Eventually it does click and this all becomes a piece of cake.

 

[markayash]

I am learning, last year I battled mustard algae all summer so in the spring I drained and pressure washed and refilled..I also went from a single filter cartridge to 4 cartridge which has helped a lot..Last year I was cleaning the cartridge every 2 weeks ( I have a lot of tree's above my pool ).